\(\dfrac{3}{x-2}=\dfrac{-2}{x-4}\left(dk:x\ne2;x\ne4\right)\)

\(\Rightarrow3\cdot\left(x-4\right)=-2\cdot\left(x-2\right)\)

\(\Rightarrow3x-12=-2x+4\)

\(\Rightarrow3x+2x=4+12\)

\(\Rightarrow5x=16\)

\(\Rightarrow x=\dfrac{16}{5}\left(tm\right)\)

\(ĐK:x\ne2;x\ne4\\ Có:\dfrac{3}{x-2}=\dfrac{-2}{x-4}\\ \Leftrightarrow3\left(x-4\right)=-2\left(x-2\right)\\ \Leftrightarrow3x-12=-2x+4\\ \Leftrightarrow3x+2x=4+12\\ \Leftrightarrow5x=16\\ \Leftrightarrow x=\dfrac{16}{5}\left(TM\right)\\ Vậy:x=\dfrac{16}{5}\)

x : 15 = 133

x = 1995

\(\Rightarrow x:15=133\\ \Rightarrow x=133\times15=1995\)

\(a.13.\left(78+22\right)=13.100=1300\)

\(b.25.70+28.25+25.2=25.\left(70+28+2\right)=25.100=2500\)

\(c.\dfrac{15.3.14.2.19}{19.14.15}=6\)

\(d.\dfrac{132.70.60}{12.35.20}=\dfrac{11.12.35.2.20.3}{12.35.20}=66\)

\(5^x-2-3^2=2^4-\left(2^8x2^4-2^{10}x2^2\right)\)

\(5^x-2-3^2=2^4-\left(2^{8+4}-2^{10+2}\right)\)

\(5^x-2-3^2=2^4-\left(2^{12}-2^{12}\right)\)

\(5^x-2-3^2=2^4-0\)

\(5^x-2-3^2=2^4\)

\(5^x-2-9=16\)

\(5^x-2=16+9\)

\(5^x-2=25\)

\(5^x=25+2\)

\(5^x=27\)

Bởi vì 27 không phân tích được 1 số có số mũ là 2

\(\Rightarrow\) Không tồn tại x

\(5^{x-2}-9=16-\left(256.16-1024.4\right)\)

\(\Rightarrow5^{x-2}-9=16-\left(4096-4096\right)\)

\(\Rightarrow5^{x-2}-9=16-0\)

\(\Rightarrow5^{x-2}-9=16\)

\(\Rightarrow5^{x-2}=25\)

\(\Rightarrow x-2=25:5\)

\(\Rightarrow x-2=3\)

\(\Rightarrow x=5\)

\(5^{x-2}-3^2=2^4-\left(2^8\cdot2^4-2^{10}\cdot2^2\right)\)

\(\Rightarrow5^{x-2}-3^2=2^4-\left(2^{12}-2^{12}\right)\)

\(\Rightarrow5^{x-2}-9=16-0\)

\(\Rightarrow5^{x-2}=16+9\)

\(\Rightarrow5^{x-2}=25\)

\(\Rightarrow5^{x-2}=5^2\)

\(\Rightarrow x-2=2\)

\(\Rightarrow x=2+2\)

\(\Rightarrow x=4\)

Vậy: x=4

a) 5x + 7x + x = 169

12x + x = 169

13x = 169

x = 169 : 13

x = 13

b) x + x + x - 2 = 13

3x - 2 = 13

3x = 13 + 2

3x = 15

x = 15 : 3

x = 5

Bang18

Bằng 18

3-4+7-5+8-6+9-10+13-11+14

=18 nhé

k cho mình với nhé

a) \(\dfrac{1}{7}< \dfrac{x}{35}< \dfrac{2}{5}\)

\(\Rightarrow\dfrac{5}{35}< \dfrac{x}{35}< \dfrac{14}{35}\)

\(\Rightarrow5< x< 14\)

b) \(\dfrac{5}{13}< 2-x< \dfrac{5}{8}\)

\(\Rightarrow2-\dfrac{5}{8}< x< 2-\dfrac{5}{13}\)

\(\Rightarrow\dfrac{11}{8}< x< \dfrac{21}{13}\)

ai mần tr mình cho tích

a) ta có:\(\dfrac{1}{7}=\dfrac{1.5}{7.5}=\dfrac{5}{35}\);\(\dfrac{2}{5}=\dfrac{2.7}{5.7}=\dfrac{14}{35}\)

\(\Rightarrow x\in\left\{6;7;8;9;10;11;12;13\right\}\)

b)ta có:\(2-x=\dfrac{5}{9};\dfrac{5}{10};\dfrac{5}{11};\dfrac{5}{12}\)

\(\Rightarrow x=2-\dfrac{5}{9};2-\dfrac{5}{10};2-\dfrac{5}{11};2-\dfrac{5}{12}\)

\(\Rightarrow x=\dfrac{13}{9};\dfrac{3}{2};\dfrac{17}{11};\dfrac{19}{12}\)

a.

\(A=B\)

\(\Leftrightarrow\dfrac{x+2}{x-2}-\dfrac{x-2}{x+2}=\dfrac{-16}{x^2-4}\);ĐK:\(x\ne\pm2\)

\(\Leftrightarrow\dfrac{\left(x+2\right)^2-\left(x-2\right)^2}{\left(x-2\right)\left(x+2\right)}=\dfrac{-16}{\left(x-2\right)\left(x+2\right)}\)

\(\Leftrightarrow\left(x+2\right)^2-\left(x-2\right)^2=-16\)

\(\Leftrightarrow x^2+4x+4-x^2+4x-4+16=0\)

\(\Leftrightarrow8x+16=0\)

\(\Leftrightarrow8\left(x+2\right)=0\)

\(\Leftrightarrow x=-2\left(ktm\right)\)

Vậy không có giá trị x thỏa mãn A=B

b.

\(A:B=\dfrac{\left(x+2\right)^2-\left(x-2\right)^2}{\left(x-2\right)\left(x+2\right)}:\dfrac{-16}{\left(x-2\right)\left(x+2\right)}< 0\)

\(\Leftrightarrow\dfrac{x^2+4x+4-x^2+4x-4}{-16}< 0\)

\(\Leftrightarrow\dfrac{8x}{-16}< 0\)

\(\Leftrightarrow\dfrac{8x}{16}>0\)

\(\Leftrightarrow\dfrac{x}{2}>0\)

\(\Leftrightarrow x>0\)